In recent years, as an environmentally friendly vehicle, a vehicle has been drawing attention which has a power storage device (such as a secondary battery or a capacitor) and which travels using driving power generated from electric power stored in the power storage device. Examples of such a vehicle include an electric vehicle, a hybrid vehicle, a fuel cell vehicle, and the like.
In order to further reduce environmental load, these vehicles are required to reduce fuel consumption and electric power consumption so as to improve energy efficiency.
Japanese National Patent Publication No. 2008-520485 (PTL 1) discloses a hybrid vehicle including an internal combustion engine and a motor generator, wherein the motor generator is controlled such that a first interval and a second interval are alternately repeated while the motor generator is in a power generator mode. In the first interval, the motor generator is driven to output high power larger than actual electric power consumption of an electric system of the vehicle. In the second interval, the motor generator is switched off.
According to Japanese National Patent Publication No. 2008-520485 (PTL 1), while the motor generator operates as a power generator, the motor generator is driven at an operating point of high efficiency in the first interval, and the motor generator is stopped in the second interval. In this way, the motor generator is suppressed from being continuously driven in a state of low efficiency during the power generation operation, thereby improving energy efficiency of the vehicle during the power generation operation.
Meanwhile, Japanese Patent Laying-Open No. 2010-6309 (PTL 2) discloses a hybrid vehicle including an internal combustion engine and a motor generator, wherein traveling using driving power generated by the internal combustion engine and traveling in an inertia state with the internal combustion engine being stopped are alternately repeated. In this way, the internal combustion engine can be driven at an operating point of high efficiency, thereby achieving improved fuel consumption.